Efforts are underway to recover two teenage swimmers who went under while struggling in the Atlantic City surf on Thursday.

Authorities were alerted about 7 p.m. Thursday that two beachgoers had been struggling and gone under, according to the U.S. Coast Guard.

Later in the evening, Atlantic City Beach Patrol Chief Steve Downey told the Press of Atlantic City that the operation had become a recovery effort.

The search continued into the evening before being called off after darkness. Efforts were resuming Friday.

The search was concentrating on the beach off Martin Luther King Boulevard.

"This is a tough beach. The undercurrent is very rough," Atlantic City Mayor Don Guardian told the Press.